CS4341 Introduction to Artificial Intelligence
Project 2 - C 2002
Solutions to Part I
Part I
Forward Chaining
RULE PREMISES TREE
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R1
Asset ?x low Asset (?x) bob low
Salary ?x low |
salary (?x) bob low
Succeeds
WM <--WM U {credit bob bad}
---------------------------------------------------------------
R2
Asset ?x low asset (?x)bob low
Salary ?x high |
salary (?x)bob high
Fails against WM
---------------------------------------------------------------
R3
Asset ?x high asset (?x)sue high
Succeeds
WM <--WM U {credit sue good}
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R4
/ \
/ \
/ \
Asset ?x ?y asset (?x)bob (?y)low asset (?x)sue (?y)high
| |
married (?x)bob (?z)mary married (?x)sue (?z)bill
succeeds succeeds
WM <--WM U {asset mary low} WM U{asset bill high}
Working memory now is:
salary bob low
asset bob low
married bob mary
parent bob bill
asset sue high
married sue bill
credit bob bad
credit sue good
asset mary low
asset bill high
Second pass
---------------------------------------------------------------
R1
/ \
/ \
/ \
Asset ?x low asset (?x)bob low asset (?x)mary low
| |
salary (?x)bob low salary (?x)mary low
(credit bob bad already in WM) Fails against WM
---------------------------------------------------------------
R2
/ \
/ \
/ \
Asset ?x low asset (?x)bob low asset (?x)mary low
Salary ?x high | |
salary (?x)bob high salary (?x)mary high
Fails against WM (again) fails against WM
---------------------------------------------------------------
R3
/ \
/ \
/ \
Asset ?x ?y asset (?x)sue high asset (?x)bill high
Success Success
(credit sue good already in WM) WM <--WM U {credit bill good}
---------------------------------------------------------------
R4
/ | | \
/ | | \
/ | | \
asset bob low asset sue high asset mary low asset bill high
| | | |
married bob mary married sue bill married mary ?z married bill ?z
succeeds succeeds succeeds fails againt WM fails against WM
{asset mary low {asset bill high
already in WM} already in WM}
Working memory now is:
salary bob low
asset bob low
married bob mary
parent bob bill
asset sue high
married sue bill
credit bob bad
credit sue good
asset mary low
asset bill high
credit bill good
Third Pass
No changes
Final working memory is:
salary bob low
asset bob low
married bob mary
parent bob bill
asset sue high
married sue bill
credit bob bad
credit sue good
asset mary low
asset bill high
credit bill good
Backward Chaining
G1: credit bob good
/ \
---------------------------------------------------------------------------
R2
Asset ? low asset (?x)bob low |
(succeeds) |
salary ?x low salary (?x)bob low |
Fails against WM and rules |
|
---------------------------------------------------------------------------
R3 |
Asset ?x high asset (?x)bob high
|
----------------------------------------------------------------------------
R4 asset (?x)sue (?y)high
|
married (?x)sue (?z)bob
Fails against WM and rules
G2: credit mary bad
|
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R1 |
Asset ?x low asset (?x)mary low
Salary ?x low |
|
--------------------------------------------------------------------------
R4 |
Asset ?x ?y asset (?x)bob (?y)low
Married ?x ?z(mary) married (?x)bob (?z)mary
Success WM <--WM U {asset mary low}
|
--------------------------------------------------------------------------
(go back to continue with R1)
R1 |
salary (?x)mary low
Failes agains WM and Rules
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